Silent electric switch



Filed Nov. 24, 1945 2 Sheets-Sheet l E' i-l 27 7-53- 4 4 4 Inn 1 5 2 Nov. 28, 1950 L. MANNON 2,531,452

SILENT ELECTRIC swrrcn INVENTOR LOYD MANNON mum @44 WWW".

ATTORNEYS Nov. 28, 1950 L. MANNON 2,531,452

SILENT ELECTRIC SWITCH Filed Nov. 24, 1945 2 Sheets-Sheet 2 INVENTOR l L OY D M A N N o N mmflau m ATTORNEYS Patented Nov. 28, 1950 UNITED STATES PATENT- OFFICE 2,531,452 SI LENT ELECTRIC SWITCH Lloyd Mannon, San Francisco, Calif.

Application November 24, 1945, Serial No. 630,578

4 Claims. 1

An object of my invention is to provide a silent electric switch which is silent in operation and which makes use of a quantity of mercury that is placed in an arcuate portion of a rotatable container, the container having electrodes extending into the interior thereof so that they will be electrically connected together by the mercury when the container is rotated into one position and will be freed from the mercury when the container is rotated into another position.

A further object of my invention is to provide a device of the type described which is extremely simple in construction and in which the electrodes are made wedge-shaped in cross section to aid them'in entering the mercury when the switch is closed, and for leaving the mercury when the switch is opened. Novel means is provided for preventing the mercury from flowing beyond the electrodes when the switch is closed. Novel means is also provided for yieldingly holding the switch in open or closed position.

Still a further object of my invention is to provide a switch that will open or close a circuit with a minimum amount of movement and that is composed of a minimum number of wearable parts. The switch is so constructed that the shock and wear on its moving parts is eliminated.

Other objects and advantages will appear in the following specification, and the novel features of the device will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming a part of this application, in which:

Figure 1 is a front elevation of the switch;

Figure 2 is a vertical section taken substantially W along the line 2-2 of Figure 1, but showing the switch in open position;

Figure 3 is a transverse section taken substantially along the line 33 of Figure 2, and shows the switch in open position;

Figure 4 is a View similar to Figure 3, but shows the switch closed;

Figures 5 and 6 illustrate two views of the mercury container showing it in open and closed positions;

Figure '7 is a perspective view of one of the electrodes used with the switch;

. ing from the spirit and scope of the invention.

In carrying out my invention, I provide a switch box indicated generally at A and this box is placed in the usual wall recess i formed in a wall or other supporting surface, indicated generally at B. The box has an inwardly extending flange 2 that is provided with threaded bores 3 for receiving screws 4, these screws being passed through openings 5 in a face plate C made of insulating material or the like and entering the threaded bores 3 for securing the plate in 'position. The cover plate C is shown in Figures 1, 2, 3, 1G and 12, as being provided with inwardly extending insulating lugs 8 and 1. Figure 2 shows a condiut 8 entering the box A and wires 9 and it! lead from the conduit and are secured to the lugs 6 and l by screws II and I2.

The face plate C has an opening it for receiving a bearing l t and the bearing rotatably carries a rotatable stop D shown in detail in Figures 2 and 3. The stop has a cylindrical portion I 5 that is rotatably received in the bearing and has a reduced shank it that enters a recess ll provided in a switch handle E. A pin 18 secures the switch handle to the shank so that a swinging of the handle E from off to on position, as shown in Figure 1, will rock the stop D.

' Figure 8 illustrates a cylindrical form of mer cury container;

1 cuate portion 22.

coincides with the axis of the stop D. The innerface 19a of the end it has a ring ltia mounted on the cylindrical portion l5 and bearing against the inner surface 2'! of the plate C, see Figure 2, and prevents the stop D from moving to the left in Figure 2. The mounting of a second ring [6a on the shank I6 causes this ring to contact with the outer face of the plate C and prevent longitudinal movement of the stop D to the right in Figure 2.

A container indicated at F in Figures 5 and 6 is made of an insulating material such as glass and has an arcuate portion 28 concentric with the container axis and side walls 29 and 30, see Figures 2 and 6. The side wall 28 carries a cylindrical projection that is received in the recess 26 of the rockable stop D and is secured in the recess by any suitable adhesive or cement. A rocking of the stop by the switch handle E will also rock the container.

The container has a fiat edge wall 32 that is disposed opposite the curved wall, see Figure 5, and a quantity of mercury G is placed in the container. Electrodes H are disposed in the container and enter the container from the fiat side 32. Figure 5 shows how the electrodes extend at an angle with respect to the side 32, so that the free ends of the electrodes will be placed near the corner 33 of the container. When the switch is in on position, the container will be in the position shown in Figure 6.

Reference to Figure '7 shows that each electrode H is wedge-shaped in cross section so as to provide a knife-like edge 34. The electrodes H are mounted in the container so that the knife edges 34 will face toward the ball of mercury and knife into the mercury as the container F is swung from the 01f position shown in Figure 5, into the on position shown in Figure 6. The electrodes will back out of the mercury G more readily when the switch is turned off due to their being wedgeshaped in cross section. Wires 35 and 35 lead from the electrodes H to the binding posts II and I2 mounted on the insulating lugs 6 and I, see Figure 3. In this Way the wires 35 and 35 are electrically connected to the wires 9 and [0.

Figures 3 and 4 show the rotatable stop D in two positions and illustrate how the stop is held in either of its two extreme positions by a leaf spring 3'1. The spring 31 is secured to a projection 38 which is integral with the face plate C and extends inwardly from the inner surface 2'. of the plate. Screws 39, or other suitable fastening means, secure the leaf spring to the lug. When the switch is in off position, the shoulder 24 is spaced slight distance from a stationary stop 46 mounted on the inner surface 2? of the face plate. The leaf spring 31 will contact with the flat edge 2| of the rotatable stop D and holds the shoulder 24 away from the stationary stop 40. The leaf spring will hold the container F in off position.

When now the switch arm E is swung from off to on position, the shoulder 25 will be moved near to the stop 40, see Figure 4, and the fiat spring 31 will contact with the flat edge 2| of the rotatable stop. During the movement of the switch from off to on position, the spring 31 is flexed slightly when it is caused to ride lip over the arcuate portion 22. There is no snapping sound caused by the spring as it rides over the arcuate portion 22. Furthermore, the flat spring 31 will bring the rotatable stop to a standstill before either of the shoulders 24 and 25 strike the fixed or stationary stop 4!]. The result is a silent operating switch. The shoulders and stationary stop are merely for the purpose of preventing the switch handle E from being manually rotated in the wrong direction. The spring will have a tendency to hold the rotary stop in either off or on position, due to the fact that either one of the fiat edges 20 and 2| is contacted by the spring and will be held against accidental rotation.

From the foregoing description of the various parts of the device, the operation thereof may be readily understood.

When the switch arm is rocked, the container F will also be rocked and the mercury G will remain at the lower part of the arcuate portion 28. When the container is brought to a stop in either closed. or open position, the mercury will have no tendency to keep on moving because it will strike the flat side 32 of the container. This is especially true when the switch is in closed position and it is this arrangement that causes the switch to complete an electric circuit when the mercury electrically connects the electrodes H. There will be no tendency for the mercury to flow beyond the electrodes to momentarily break the circuit. The rotatable stop D also acts as a device for holding the switch in closed or open position.

In Figure 9 I show a slightly modified form of mercury switch. In this figure the container J is of the same shape as the container F, but the I central electrode indicated at K is in the shape of a Y. One branch 4| of the electrode K cooperates with another electrode L for closing a circuit between wires 42 and 43 when the container J is in the position shown. The container J will be mounted on the rotary stop D and the device will operate in the same manner as that shown in Figure 1, except that it will act as a doublethrow switch.

In Figure '10 I show a container N that is of the same shape as that disclosed in a joint application of Lloyd Mannon and Edward W. Coleman, Serial No. 592,582, filed May 8, 1945, now abandoned, on a Safety Control for Motion Picture Films. The container is cylindrical in shape and the electrodes P extend down into the mercury Q as illustrated. A rotation of the cylindrical container N will move the electrodes P out of the mercury to open the switch.

The switch casing may be cyindrical or semicylindrical and the principle involved is the same, namely: the raising of the electrodes out of the mercury to break an electric circuit and the moving of the electrodes into the mercury to close the circuit. Gravity maintains the quantity of mercury at the bottom of the casing at all times as the casing is revolved. Enough mercury is used to completely submerge the ends of the electrodes to a depth of about one-sixteenth of an inch when the switch is closed, and sufficient mercury is used to overcome the cohesion between the mercury and its supporting surface. The mercury will therefore not have any tendency to follow the container periphery as it is rotated.

The are formed by the cylinder is great enough so that the portion adjacent the mercury will be at an angle which will permit it to readily slide under the mercury instead of tending to push against the body of mercury and carry it with it. The electrodes in entering the mercury, meet with resistance due to the density and surface tension' of the mercury. The making of the electrodes wedge-shaped in cross-section and the causing of the knife-like edges of the electrodes to enter the mercury first, reduces this resistance and friction to a minimum. Low resistance metal is used'for the electrodes and this permits them to be made small in thickness and thus enter the mercury more readily.

A vacuum is preferably formed within the container housing the mercury. The container is provided with a nipple to permit the container to be evacuated of air more readily and after this is accomplished the nipple is sealed. The nipple also aids in securing the container in place.

I show another modified form of silent switch control in Figures 10, 11 and 12. In this form a hollow rotatable stop R is used and theshape of the stop is similar to the stop D. The stop is provided with two spaced disc plates 44 and 45 that have shoulders 36 and 41. These shoulders function in the same manner as the shoulders 24 and 25 on the stop D. Figure illustrates the shoulder ll spaced a slight distance away from the stationary stop Ml, while Figure 11 shows the shoulder 46 spaced a slight distance away from the same stop 40.

A pair of coil springs 48 and 49 are connected to a common pin 50 which is carried by the stop R. The spring 48 has its other end connected to the face plate C by means of a pin 5!, while the spring d9 has its free end connected to the same face plate by a pin 52. A line drawn through the two pins 5i and 52 also extends across the axis of the stop R.

The spring 48 is stronger than the spring 49 and the tension of the two springs is designed so that they will balance each other equally when the stop R is in the position shown in Figure 10 and also when the stop is in the position shown in Figure 11. In either position, the pin 50 will be disposed the same distance away from the straight line extending between the pins 5i and 52. In Figure 10 the pin will be disposed on one side of the line, while in Figure 11 it will be disposed on the other side of the line. A person rotating the switch handle E from on to Oh position, or vice versa, merely rotates the stop R until the two springs are in alignment with each other; Further movement or the handle E will permit the spring 43 to rotate the stop R past dead center position, and then the stop will assume the position shown in Figure 11. As already stated, the two springs will come into equalbalance with each other before either the shoulder 46 or the shoulder 41 strikes its side of the stationary stop 40. The purpose of the stationary stop and the shoulders is to prevent the handle E from being rotated in the wrong direction when manually opening or closing the switch. The switch is silent in operation.

A good portion of the springs 48 and 49 are received within the hollow rotatable stop R. Figure 12 illustrates the disc plate 44 provided with a cylindrical hollow hub 53 that in turn receives the cylindrical portion 3| of the mercury container F. The mercury container will be rotated by the stop R into closed and open position for closing or opening the switch. In all other respects the form of the invention shown in Figures 10 to 12, inclusive, is the same as in the other form and will operate in the same manner.

The flat spring 3'! creates sufficient force to complete the rotation of the stop D from off to on position or vice versa when the switch handle E has swung the stop to a position where the arcuate portion 22 starts to move beyond the dead center position. The spring 48 is strong enough to rotate the stop R to its on or off position after the switch handle has rotated the stop past dead center. In both the stops D and R, the action will be silent. The material com- 6 posing the faceplate C is insulating material such as Lucite, Plexiglas, etc.

I claim:

1. In a silent electric switch, a rockable member, a shaft connected to the member, a pair of springs connected to a common point on the member which is disposed a predetermined distance from the center of the member, the outer ends of the spring extending substantially in opposite directions from said common point and being secured to fixed points that lie in a dead center line intersecting the center of the member, one of the springs being stronger than the other and continuing to rock the member beyond dead center when the shaft has been manually rotated to move the member slightly beyond dead center, the other spring acting as a silent stop for bringing the member to a, predetermined stop on either side of dead center when the forces of the two springs are balanced.

2. In a silent electric switch, a rockable member, a shaft connected to the member, a pair of springs connected to a common point on the member which is disposed a predetermined distance from the center of the member, the outer ends of the spring extending substantially in opposite directions from said common point and secured to fixed points that lie in a dead center line intersecting the center of the member, one of the springs being stronger than the other and continuing to rock the member beyond dead center when the shaft has been manually rocked to move the member slightly beyond dead center, the other spring acting as a silent stop for bringing the member to a predetermined stop on either side of dead center when the forces of the two springs are balanced, a stationary stop for the member, said member having shoulders "angularly spaced from each other, either one of which is disposed close to the stop, but is spaced a slight distance therefrom when said member comes to rest in either one of its two predetermined stop positions, said stop lying in the path of the shoulders and preventing rocking of the member an appreciable distance beyond the two extreme positions determined by the balancing forces of the two springs on either side of the dead center line.

3. In a silent switch, a rotatable switch closing and opening member swingable past a dead center position for either of its movements, a stationary stop for said member, means for rocking the member including a spring for urging the member into its switch opening or closin position after the member has been moved past the dead center position, and spring means for balancing the force of the first spring when the member reaches either its switch closing or opening positions at a point spaced from said stop whereby the member will be brought to a silent stop in either of its positions.

4. In a silent electric switch, a plate, a shaft, a rotatable member connected to said shaft, a stationary stop secured to said plate and lying in the arcuate path of said member, a pair of springs connected to a common point on the member said point being offset from the axis of rotation of the member, the outer ends of the springs extending substantially in opposite directions from said common point and being secured to fixed points lying in a dead center line intersecting the center of said member, one of said springs being stronger than the other and causing continued movement of said member when the member has been rotated beyond 7 said line, the other spring being of such strength Number in comparison to the stronger spring to balance 843,070 the force of said spring when the member 919,535 reaches a predetermined point spaced from said 1,569,965 stop. 1,658,619 LLOYD MANNON. 1,902,926 1,982,717 REFERENCES CITED 2 314 714 The following references are of record in the file of this patent: 10

Number UNITED STATES PATENTS 20,670 Number Name Date 21,551

445,752 Hofiman Feb. 3, 1891 529,578 Badt Nov. 20, 1894 Name Date Button Feb. 5, 1907 Calhoun Apr. 27, 1909 Chapin Jan. 19, 1926 Walker Feb. '7, 1928 West et a1 Mar. 28, 1933 Wilhelm Dec. 4, 1934 Kouyoumjian Mar. 23, 1-943 FOREIGN PATENTS Country Date Great Britain Sept. 17, 1907 Great Britain Oct. 7, 1903 

